During a sale at a bookstore, joseph buys a book at full price. he is given a 50 percent discount on a second book of equal or less value. if joseph buys two books with full price values of $15 and $10 respectively, what is the total percent cost reduction during the sale of the two books ?

Your vet has placed your pet on a diet. the diet is to contain at least 12 mg of fat and at least 14 mg of protein per serving. these requirements are to be obtained from two food sources. source a contains 2 mg of fat and 2 mg of protein per serving. source b contains 1 mg of fat and 3 mg of protein per serving. if source a sells for $1.28 per serving and source b sells for $1.12 per serving, how many servings of each type should be purchased to satisfy the requirements at minimal cost?